Double valve bag



1962 R. J. TOMSON 3,050,235

DOUBLE VALVE BAG Filed Oct. 6, 1960 2 Sheets-Sheet l 73 7'4- AvmwmnRichard J- TOMSON "Zita- United States Patent 3,050,235 DOUBLE VALVE BAGRichard Johann Tomson, Ville St. Laurent, Quebec,

Canada, assignor to Du Pont of Canada Limited, Montreal, Quebec, Canada,a corporation of Canada Filed Oct. 6, 1960, Ser. No. 60,904 Claimspriority, application Canada Sept. 1, 1960 4 Claims. (Cl. 229-625) Thisinvention relates to plastic bags and more particularly to plastic bagshaving tWo sleeved filling openings at one corner thereof called valves.

The use of plastic bags in packing is growing every day. Theapplications are numerous particularly in bagging materials calling forhigh moisture protection or chemical resistance. They are employedespecially with finely divided granular pulverized and powdery materialsuch as ammonium nitrite, urea, polyethylene resin granule, dry acids,cement, etc. Plastic bags are also sought after for their effectivestriking appearance.

Problems connected with the use of plastic bags however, especially inheavy-duty shipping have deterred the use thereof, one of the drawbacksbeing bag failure. Other disadvantages are the handling problemsstemming from the slipperiness of the material and also some powderymaterials rendering the sealing problem acute.

It is therefore, a primary object of this invention to overcome theshort-comings and disadvantages of plastic bags heretofore in use.Another object is to provide a plastic bag having failure proof cornersadapted for heavyduty shipping. A further object is to provide a plasticbag having corners which are extra strong, simple in construction, easyto manufacture and adapted for heavy duty shipping. A still furtherobject consists in having the plastic bags entirely produced in the bagmaking factory which eliminates all further heat-sealing or closingoperation. A particular object of this invention is to provide a plasticbag having two valves at one corner thereof, which are closed by theinside pressure of the material when the bags are turned upside down.These and other objects and advantages will become apparent from thefollowing description of the invention.

Referring now to the drawings:

FIGURE 1 is a perspective View of a bag made in accordance with thepresent invention;

FIGURE 2 is a fragmentary view showing the two valves of the bag;

FIGURE 3 is a perspective view illustrating a cutting pattern of thegussetted tubular plastic material used to make the bag;

FIGURE 4 is a side elevational view with parts broken away showing theheat-sealing point of the bag;

FIGURE 5 is a diagrammatical cross-sectional view along line 5-5 ofFIGURE 4;

FIGURE 6 is a diagrammatical cross-sectional view along line 66 ofFIGURE 4;

FIGURE 7 is a fragmentary cross-sectional top view of the folding of thetwo sleeves to form the valves;

FIGURE 8 is a fragmentary view of the construction of a bottom corner.

Referring now to the various figures wherein like parts will be referredto by the same reference characters, 10 is a gussetted flat tube ofsuitable plastic material having atone corner thereof extension 11.

The gusset 12 is formed by two outer creases of folds 13, 14 and oneinner crease 15, similarly gusset 16 is formed by outer creases 17 and18 and inner crease 19. The term gusset is herein used to mean theinwardly directed area of the plastic tube divided in two portions bothfacing each other, which is caused by creasing the plastic tube at lines13, 14 and 15, and 17, 18 and 19, as shown in FIGURES 1, 3 and 4. Toform valves, the exice tension 11 is vertically cut 20 at line of crease15 as shown in FIGURE 3; the two resulting parts 21 and 22 of theextension 11 hereinafter referred to as sleeves 21 and 22 are thenfolded inside the bag along lines of fold 23 such that they projectinwardly thereof parallel to the top 24 as shown in FIGURES 1, 2 and 4.Two valves are thus obtained 25 and 26. At the three non-valved cornersof the bag the two portions facing each other formed by the divided areaof the gusset are respectively diagonally heat-sealed at approximately45 to the externally adjacent side of the bag as indicated by referencecharacters 27 at the top 24 and 28 at the bottom 29 of the bag. The top24 and bottom 29 of the tubular material are then heat-sealed in theirentire widths to form the bag. In this manner no material contained inthe bag can penetrate into the triangular shaped section of the cornersat the three non-valved corners.

The two sleeves 21 and 22 which form the valves 25 and 26 are in arectangular form as shown in the various figures of the drawings.However, in order to provide the plastic bag with a more secure closure,the two sleeves 21 and 22 or one of them can be in a trapezium form,which is disclosed and illustrated in applicants copending applicationCanadian Serial No. 798,639.

For filling purposes a filling tube or spout of a packing machine isinserted into one of the valves and the material is fed into the bagwhile the air which is trapped in the bag and forced into it escapesthrough the other valve, which permits equalizing the inside and outsidepressures. This makes it possible to obtain a maximum load in the bag.If desired, a tube connected with a slight vacuum source can be insertedthrough the valve which is not used for filling. It goes without saying,that in order to shorten the filling time both valves can be usedsimultaneously for filling the bag.

After being filled the bag is dropped upside down and automatically theinside pressure of the contents forces the two sleeves 21 and 22 of theextension 11 against the side and the extremity 24 of the bag which isnow the bottom, thereby closing the valves.

One would think that the contents of the bag would come out upon tippingthe 'bag, however, such is not the case. In effect, the plastic filmemployed to make these bags has an advantageous characteristic; thenwhen it is folded it does not tend to take its original position or tospring back; the creases formed are stable. Moreover, in most cases thetwo sleeves 21 and 22 are nicely folded. However, if it is desired toobtain a more uniform folding of the sleeves 21 and 22 the outer sidesof the two sleeves 21 and 22 are longitudinally heat-sealed about theirmiddle to the adjacent side of the bag as shown in FIGURES l, 2 and 4.

There is no supplemental sheet sleeve or valve lining needed to securethe closure of the valve. The construction of the corners of the bagmade in accordance with the present invention remarkably improves theappearance of the bag by forming well shaped rectangular corners afterthe bag is filled as shown in FIGURE 4, this greatly reinforces thestrength of the corners and also provides the bag with outside emptypockets at each nonvalved corner which furnishes an excellent means forlifting and carrying purposes. The closed triangular shaped sectionslocated at each non-valved corner are considered as an important featureof the invention.

The invention also contemplates the printing, if so desired, of the flatplastic tube at desirable areas before filling the bag.

An heat-scalable plastic material can be employed to form the bag ofthis invention the only limitation being the heaviness and specialchemical requirements of the material for which the bag is designed.

It is to be understood that various modifications could 7 3 be made inthe above construction shown and described Without departing from thescope of the invention.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A bag formed from a flattened tube of heat-sealable thermoplasticmaterial, having a single gusset at each side, said tube being heatsealed at each end, having an integral extension in one corner, saidextension comprising the section of the tube forming one gusset and theadjacent walls of the bag, each half of said extension comprising oneside of said gusset and the adjacent wall of the bag being independentlyfolded inwardly in such a manner that the line formed by the side of thegusset and the adjacent Wall of the bag will be rotated through an angleof substantially 90", forming two adjacent valve filling inlets.

2. A bag as claimed in claim 1 in which the two walls of at least twoofthe non-valved corners are heat-sealed at approximately 45.

3. A bag as claimed in claim 1 wherein the two outerwalls of said valveare heat-sealed to the adjacent walls of said bag.

4. A bag as claimed in claim 1 in which said thermoplastic material ispolyethylene having a specific gravity of .9125 to .975.

References Cited in the file of this patent UNITED STATES PATENTS1,356,114 Rose Oct. 19, 1920 2,378,285 Contryman June 12, 1945 2,811,300Landell Oct. 29, 1957 FOREIGN PATENTS 496,642 Italy July 28, 1954

